Propulsion system for yachts, trawlers and the like

ABSTRACT

The present invention provides a propulsion system mounted in the hull of a marine vessel. The system includes a conduit system with water intake openings defined in the port and starboard portions of the hull adjacent the bow. Water intake conduits conduct water from the water intake openings to a collection chamber. Water discharge conduits conduct water from the collection chamber to water discharge openings. At least one impeller is mounted in each of said discharge conduits. A valve system is mounted in the conduit system and is selectively operable to isolate the system and prevent the flow of water through the system. A water pump may be used to evacuate water from the system when the valves are closed. A further preferred feature provides access to the impeller portion of the propulsion system. A conduit extension section diverges from the conduit system with one end above the level of the vessel&#39;s waterline. A sealable hatch is mounted to the conduit extension.

RELATED APPLICATION

This application claims priority to provisional application Ser. No.60/236,071, filed Sep. 28, 2000. The provisional application is herebyincorporated by reference.

FIELD OF THE INVENTION

Preferred embodiments of the present invention deal with propulsionsystems, and more particularly with an improved impeller or water jetsystem and method for propelling marine vessels such as yachts, trawlersand the like.

BACKGROUND OF THE INVENTION

Marine vessels, such as yachts, trawlers, ships and boats, are known touse various propulsion systems. A conventional propulsion systemincludes a propeller or “prop” mounted underneath and/or behind the hullof the vessel on a driveshaft extending from an engine compartment. Whenthe propeller is driven to provide thrust, the vessel is pushed forward;however, such systems suffer in efficiency since a propeller pushes somewater in directions other than the preferred direction of thrust.Moreover, the extended propeller and drive shaft can impact objects orthe ground, can be fouled in seaweed, lines or other debris, can developmarine growths or can impact other items such as sea creatures,potentially damaging the propeller or the object encountered. This canbe particularly dangerous in yachts or similar sized boats where peoplemay be swimming or diving near the vessel.

One alternative to a conventional propeller is an impeller propulsionsystem also known as a water jet system. An impeller system pulls waterthrough a water intake opening (typically located underneath and towardsthe middle to stern of the vessel) and then forces it through a channeland out through a discharge opening to propel the vessel. An impellersystem typically includes a propeller or pumping mechanism mountedwithin the channel which is used to accelerate and focus the watermovement. The expelled water force or jet pressure pushes the vesselforward. Conventional impeller systems frequently suffer from highmaintenance needs, turbulence and cavitation within the channel, andfrequently require a larger engine capacity and/or an engine operatingat higher rpm.

Further, in waves or chop, the vessel may move so that the water intakeopening(s) are exposed to air, introducing air bubbles into the system,causing a sudden reduction in resistance. Excess air can result in amomentary release of the propeller, i.e. cavitation, allowing the engineto rev too quickly and potentially damaging the engine. Accordingly,there is a need for an improved propulsion system.

In conventional and impeller systems, the propeller and shaft arenormally exposed to the ambient water whenever the vessel is afloat.This exposes the metal and equipment to rust, debris and marine growthresulting in increased maintenance costs, especially in salt water. Dueto the mounting of the propeller and shaft under the hull or within achannel, maintenance and/or replacement is difficult. Moreover, in manysuch vessels, the propulsion equipment is not in use a large percentageof the time. Accordingly, it is also desirable to provide a propulsionsystem where exposure to ambient water is minimized and maintenance andservice can be facilitated.

The present invention addresses these needs.

SUMMARY OF THE INVENTION

A preferred embodiment of the present invention provides a propulsionsystem mounted in the hull of a marine vessel. The system includes aconduit system with water intake openings defined in the port andstarboard portions of the hull adjacent the bow and below the waterlineof the vessel. A third water intake may be defined amidship in thevessel's keel. A collection or mixing chamber is mounted within thehull. Water intake conduits conduct water from the water intake openingsto the collection chamber. Water discharge openings are symmetricallydefined in the stern of the hull. Water discharge conduits conduct waterfrom the collection chamber to the water discharge openings. At leastone impeller is mounted in each of the discharge conduits.

In an alternate preferred embodiment, the present invention provides asystem for isolating an impeller propulsion system mounted within thehull of a marine vessel. At least one water intake opening is defined inthe hull of the marine vessel. At least one water discharge opening isdefined in the stern of the hull of the marine vessel. A conduit systemextends from the water intake opening(s) to the water dischargeopening(s). At least one water intake valve is selectively operable toprevent the flow of water through the water intake opening(s), and atleast one water discharge valve is selectively operable to prevent theflow of water through the water discharge opening(s). The system mayfurther include a pump connected to the conduit system, and operable toevacuate water from the system when the water intake and the waterdischarge valves are closed.

A further preferred embodiment of the present invention provides afeature allowing access to the impeller portion of a propulsion systemmounted within a marine vessel. The impeller portion of the propulsionsystem is normally mounted in a conduit within the hull below thewaterline. A conduit extension or access tube section diverges from theconduit with a first end in open communication with the conduit adjacentthe impeller. The opposing end of the conduit extension extends abovethe level of the vessel's waterline. A sealable hatch is mounted to theopposing end of the conduit extension and may be opened to service theimpeller.

It is a preferred object of the present invention to provide propulsionsystem for a marine vessel.

It is a further preferred object of the present invention to provide animproved propulsion system which is safer and more efficient.

It is another preferred object of the present invention to provide animproved propulsion system with reduced and easier maintenance.

It is still another preferred object of the present invention to providea propulsion system which may be stored in a dry state while the vesselis still in the water.

Further objects, features and advantages of the present invention shallbecome apparent from the detailed drawings and descriptions providedherein.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cut-away, top view of a preferred embodiment of a propulsionsystem in accordance with the present invention.

FIG. 2 is a side, cut-away view of the embodiment illustrated in FIG. 1.

FIG. 3 is a side, cut-away view of an alternate preferred embodiment ofthe present invention.

FIG. 4 is a partial rear view of a marine vessel in accordance with apreferred embodiment of the present invention.

FIG. 5 is a partial side view of a marine vessel in accordance with analternate preferred embodiment of the present invention.

DESCRIPTION OF PREFERRED EMBODIMENTS

For the purposes of promoting an understanding of the principles of theinvention, reference will now be made to the embodiments illustrated inthe drawings and specific language will be used to describe the same. Itwill nevertheless be understood that no limitation of the scope of theinvention is thereby intended, and alterations and modifications in theillustrated device, and further applications of the principles of theinvention as illustrated therein are contemplated as would normallyoccur to one skilled in the art to which the invention relates.

Referring now to FIGS. 1-5, there are illustrated preferred embodimentsof the present invention, namely an impeller propulsion system for awater vessel or water craft. The vessel is schematically represented inthe Figures with vessel hull 10. The present invention is designed forlarge vessels such as yachts, trawlers and ships, but could be sized andused in smaller boats as well. A typical impeller propulsion system iscontained within a conduit system extending longitudinally within thehull of the vessel 10. The propulsion system is typically mounted withthe water intake, the conduits and the water discharges below thewaterline of the vessel. The water intake is frequently located in thekeel adjacent the middle or stern sections.

The impeller portion includes a pumping mechanism, such as a propelleror prop 40 located in a conduit and mounted on a driveshaft 142extending into an engine compartment where it is driven by an engine 42.When in use, the engine 42 drives propeller 40 forward to accelerate andforce water through the conduit, expelling the water through a dischargeorifice in the stern 16. The discharge force propels the vessel 10forward. The system can reverse the propeller direction to slow or backthe vessel, or a plate or bucket may be used to redirect the flow ofwater in a reverse or braking direction. Additionally, the propeller canbe reversed to backflush the system for maintenance. Notwithstanding theabove, forward movement is primarily discussed herein for simplicity.

FIGS. 1-2 illustrate a specific preferred embodiment of an impellerpropulsion system. FIG. 1 is a top-down view of a vessel showing across-section generally below the water line of the vessel. FIG. 1 ispartially cut-away. FIG. 2 is a cut-away, sideview of the embodimentillustrated in FIG. 1. Water intake openings 29 are defined in hull 10.In the illustrated preferred embodiment, water intake openings 29 aresymmetrically defined on the starboard and port sides adjacent to thebow 14 of the hull 10 below the vessel's waterline. A third water intakeopening 32 may be mounted amidships in the keel 12 of the hull 10. Waterintake cylinders 30 may be mounted over intake openings 29. The surfaceof water intake cylinders 30 may be grated, slotted, or otherwiseconfigured to allow water into intake openings 29 but to keep oversizeddebris or solid objects from entering the system. A similar grate orfilter is mounted over third water intake opening 32. The system canaccommodate some small particles in the water, such as sand or gravel,but preferably screens out larger objects which could potentially damagethe system lining or the propeller(s).

A conduit system carries water within hull 10. Water intake openings 29and 32 are attached to intake or feed conduits or pipes 34 which carrywater from the intake openings to collection chamber 36. Collectionchamber 36 is preferably a larger conduit or cylindrically shapedchamber. Collection chamber 36 serves as a water collection and storagepoint. The conduit system extends longitudinally within hull 10, passingthrough standard areas such as crew compartments 17, fuel tanks 18,water tanks 19 and bulkheads.

Discharge tubes or conduits 38 extend from collection chamber 36 todischarge openings or orifices 43 in the stern 16 of hull 10. Preferablythe discharge openings 43 are symmetrically arranged below the waterline to provide balanced thrust. For example, the discharge openings 43may be arranged to either side of a wet/dry garage 20, as discussed inthe incorporated provisional application and co-pending application Ser.No. 09/962,767.

Surrounding each discharge opening 43 is a reducing nozzle 44,preferably including a plurality of turbulator tabs 45 mounted aroundthe internal circumference of nozzle 44. Turbulator tabs 45 arepreferably planer pieces mounted to the nozzle to straighten thedischarged water flow and reduce turbulence and cavitation. Turbulatortabs 45 and nozzle 44 increase flow speed resulting in greater thrustefficiency. A rear view of a discharge opening 43 is illustrated in FIG.4.

Mounted within each discharge tube 38 is a pumping mechanism such as animpeller prop 40. Prop 40 is rotated by engine 42 via drive shaft 142 topropel water through the discharge tube 38 and expel it from dischargeopening 43. The displaced water creates a suction, pulling water fromcollection chamber 36, and, by extension, draws water into the conduitsystem through intake openings 29 and 32. In a preferred embodiment ofthe present invention shown in FIGS. 1-2, the cross-sectional area ofwater intake cylinders 30 is greater than the cross-sectional area ofthe intake conduits 34. The water intake openings 29 and intake conduits34 of the propulsion system are preferably sized to handle or contain upto twice the amount of water that the prop 40 requires at maximum speed.In a preferred embodiment, the cross-sectional size of the conduitsystem decreases by section from bow to stern. As an exception,collection chamber 36 may have a larger cross-sectional area to assistin its storage function.

For example, an intake cylinder 30 may have a diameter of sixty incheswhile an intake conduit 34 has a diameter of forty-eight inches. Thegreater size of the intake cylinders assists in ensuring that sufficientwater is fed into the intake conduits, minimizing the introduction ofexcess air and turbulence. At rest, water initially enters the conduitsystem to equalize the water level with the vessel's waterline. Once thevessel begins movement, the vessel's own momentum assists in feedingwater into the system.

Intake tubes 34 carry water to a large mixing or collection chamber 36,for example with a seventy-two inch cross-section. Collection chamber 36then feeds water into two forty-eight inch discharge tubes 38.Preferably collection chamber 36 stores and is fed a volume of watergreater than the supply drawn by the impellers at maximum speed. Thisallows for brief variations and interruptions in the incoming watersupply without interrupting the water supplied to the impellers. Forexample, with three intake openings, the vessel can roll or crest a wavewhere one or more of the intake openings is momentarily clear of thewater interrupting the feed, but meanwhile the other openings continueto feed water to collection chamber 36.

By storing excess water capacity, collection or mixing chamber 36further serves the function of damping turbulence within the water inthe chamber. Calmer water allows a more even water feed to dischargetubes 38 and the impellers. In a further preferred embodiment,collection chamber 36 includes an air check-valve to evacuateaccumulated excess air from collection chamber 36, but not allowing thepassage of liquid.

In one preferred embodiment, tubes 38 include internal straighteningvanes 145 to reduce turbulence. The straightening vanes 145 dampencross-currents and direct water within the conduit in the desired waterdirection and more evenly around the impeller edges. Straightening vanes145 may be mounted in conduit 38 in front of and/or behind impeller prop40.

In an alternate embodiment, illustrated in FIG. 3, a water intakeopening 32 is defined in the middle and rear of keel 12 without forwardwater intake openings. Feed tube 38 extends from intake opening 32, andis concentrically reduced 39 to become a discharge tube adjacentimpeller prop 40. Feed tube 38 can be mounted at an angle, such asforty-five degrees, to assist in feeding water into the opening. Feedtube 38 terminates in a discharge opening 43 and nozzle 44 adjacent torudders 22.

In one preferred feature, shown as an example in FIG. 3, the diameter ofeach discharge tube 38 is concentrically reduced or stepped down 39adjacent to the impeller. Using the Venturi effect, this increases theflow rate and minimizes cavitation. By way of example, feed tube 38 mayhave an initial diameter of sixty inches and is then concentricallyreduced 39 to a diameter of forty-eight inches. At the end of eachdischarge tube 38, the flow diameter is further reduced by means of aconcentric reducer or nozzle 44 with turbulator or straightening tabs 45installed around the inside circumference of the discharge opening 43.

A further preferred feature illustrated in FIG. 3 is conduit extensionor access tube 78, extending from conduit 38 adjacent to prop 40.Conduit extension 79 is connected in communication at one end to conduit38, and is sealed at the opposing end by removable hatch 80. Preferably,conduit extension 79 has sufficient height to place hatch 80 a distanceabove the water line of the vessel 10, for example twelve inches. Hatch80 is of sufficient size and may be opened when necessary to view,service or replace propeller 40. Since it is above the vessel'swaterline, hatch 80 may be opened while the propulsion system is filledwith water, although preferably not while the system is in use.Alternately, hatch 80 may be opened when the system is stored in a drystate.

Hatch 80 or other portions of the conduit system may optionally includea viewing panel 82 of glass, Plexiglas® sheets or a similar transparentmaterial to allow viewing of the area in the system, such as around theprop. This allows viewing of the waterflow and any debris while thesystem is closed and/or operating. Also optionally, a light or lightsmay be mounted within conduit 38 to assist in seeing through panel 82.

The amount of water flowing through water intake openings 29 and 32 maybe adjusted with valves depending on the surrounding waves and the speedand roll of the vessel to individually or in combination ensure a smoothand uninterrupted flow of water into chamber 36. These adjustments maybe controlled to minimize the introduction of air bubbles which can leadto internal turbulence and cavitation. Preferably the majority of wateris introduced through the forward water intakes 29, which also reducesthe water resistance as the vessel moves forward.

As a further improved feature of the present invention, the impellerpropulsion system includes a valve system. The valve system is operableto isolate the impeller portions of the system, and, when desired, toplace the impeller portions or the entire system in a dry state. Thevalve system includes intake valves 60 closable to prevent water flowthrough the water intake openings, and discharge valves 64 closable toprevent water flow through the water discharge openings. Other valves,such as middle valves 62, may optionally be used to isolate portions ofthe propulsion system.

The valves may be of standard types known in the industry and sized tohandle large diameter conduits with minimal leakage. Pressure exerted onthe valves will be relatively low, at maximum the pressure willcorrespond to the water pressure at a few feet in depth corresponding tothe depth of the hull 10. Examples of appropriate valve types includeball valves, butterfly valves, and knife gate valves. The valve systemmay further include a pump 150 connected to the propulsion system andoperable to evacuate water from the system.

The valve system may be closed when the propulsion system is not in useand/or needs maintenance (for example to service a propeller). Whileclosed, the valve system prevents the entry or exit of water, debris,swimmers or sea creatures within the system, minimizing the potentialfor damage or injury. When pump 150 is used to evacuate water from thepropulsion system, the system may be stored in a dry state even thoughthe vessel remains on the water and the system is below the waterline.Dry storage reduces the immersion of the propulsion system in water, andespecially with respect to salt water, reduces the corresponding risk ofpotential deterioration such as marine deposits, debris or rust. Beforeeach use, the valve system is opened and the water level within thesystem is allowed to equalize with the surrounding water level.

Further, the conduit systems, valves and pump may be used to regulatethe amount of water in the system. Water may be allowed into the systemto provide ballast weight, or water may be forced out of the system toprovide additional buoyancy to the vessel.

Optionally, port and starboard side thrusters 70 (illustrated in FIGS. 1and 5) may extend from discharge tubes 38 adjacent the stern of vessel10 and can be used to assist in steering. Side thrusters 70 may beopened and closed with side valves 74.

The advantages of the present impeller propulsion system versus aconventional prop/strut include:

1. There are no moving parts exposed to the outside elements below thewater line. The entire system is in the confines of the vessel.

2. Environmentally friendly by preventing prop impact with objects,animals and land.

3. Grounding of vessel cannot affect the running gear.

4. The props or propellers can be changed from inside of the vesselthrough the access hatch provided.

5. Where valves are provided, the entire system can be evacuated ofseawater. During the time a vessel is at dock or not in use (which canbe as much as 90% of its life), the propulsion system can be kept in adry state.

6. When the intakes are routed to the front of the vessel, the amount offorce it takes for the vessel to push through the seas is greatlyreduced. This effect also increases the velocity of the intake water tothe prop.

7. The midship opening 32 is preferably only used when rough seas aremaking the bow come out of the water. This feature helps stop propcavitation.

8. The front inlet tubes can be closed off during rough sea conditionsand either pumped out creating high buoyancy or left full creating heavyballast or any condition in between.

9. With the tube lighting system and viewing ports, the performance ofthe propellers can be observed from the engine room viewing ports or onscreen in color in the pilothouse.

10. State-of-the-art control devices can be installed on the tube systemthat can give exact G.P.M. flow rates and information that is unknownand only assumed on conventional underwater prop systems.

11. Rear side thrusters can also be driven through control valves atright angles off the main tube system.

The performance and features of the above propulsion system gives theboat owner a level of safety, ease of maintenance, flexibility ofoperation, and above all the most efficient, powerful system to date notto mention being environmentally friendly.

While the invention has been illustrated and described in detail in thedrawings and foregoing description, the same is to be considered asillustrative and not restrictive in character, it being understood thatonly the preferred embodiment has been shown and described and that allchanges and modifications that come within the spirit of the inventionare desired to be protected.

What is claimed is:
 1. A propulsion system mounted in a hull of a marinevessel, wherein the marine vessel defines a waterline in relation to thesurrounding water, comprising: a) at least two water intake openingsdefined in the hull below the waterline of the vessel; b) a collectionchamber mounted within the hull; c) at least two water intake conduitsextending from said water intake openings to said collection chamber; d)at least two water discharge openings defined in the stem of the hull;e) at least two water discharge conduits extending from said collectionchamber to said water discharge openings; f) at least one impellermounted in each of said discharge conduits; g) wherein said at least twowater intake openings are adjacent the bow on the port and starboardportions of the hull; and, h) at least a third water intake openingdefined in the keel of the hull and coupled to said collection chamber.2. The propulsion system of claim 1 further comprising a transparentviewing panel mounted in said water discharge conduits.
 3. Thepropulsion system of claim 1 further comprising an access hatch mountedto one of said discharge conduits adjacent one of said impellers.
 4. Thepropulsion system of claim 3 further comprising a conduit extensionhaving a first end in communication with a said discharge conduitadjacent an impeller and wherein said conduit extension has an opposingend extending above the waterline of the vessel, and wherein said accesshatch is mounted on said conduit extension.
 5. The propulsion system ofclaim 1 further comprising a plurality of valves to selectively sealsaid water intake openings and said water discharge openings.
 6. Thepropulsion system of claim 5 wherein said valves are selectivelyoperable to limit the amount of water flow through said propulsionsystem.
 7. The propulsion system of claim 1, further comprising aplurality of straightening vanes mounted within each of said dischargeconduits.
 8. A propulsion system mounted in a hull of a marine vessel,wherein the marine vessel defines a waterline in relation to thesurrounding water, comprising: a) at least two water intake openingsdefined in the hull below the waterline of the vessel; b) a collectionchamber mounted within the hull; c) at least two water intake conduitsextending from said water intake openings to said collection chamber; d)at least two water discharge openings defined in the stern of the hull;e) at least two water discharge conduits extending from said collectionchamber to said water discharge openings; f) at least one impellermounted in each of said discharge conduits; g) wherein said at least twowater intake openings are adjacent the bow on the port and starboardportions of the hull; and, h) water intake cylinders mounted over saidwater intake openings, wherein said water intake cylinders define aplurality of smaller openings to allow water into said water intakeopenings while inhibiting the passage of solid objects.
 9. Thepropulsion system of claim 8 wherein each said water intake cylinder hasa cross-sectional area greater than the cross-sectional area of eachsaid water intake conduit.
 10. A propulsion system mounted in a hull ofa marine vessel, wherein the marine vessel defines a waterline inrelation to the surrounding water, comprising: a) at least two waterintake openings defined in the hull below the waterline of the vessel;b) a collection chamber mounted within the hull; c) at least two waterintake conduits extending from said water intake openings to saidcollection chamber; d) at least two water discharge openings defined inthe stem of the hull; e) at least two water discharge conduits extendingfrom said collection chamber to said water discharge openings; f) atleast one impeller mounted in each of said discharge conduits; and, g)wherein the cross-sectional area of each of said discharge conduits isreduced adjacent to each said impeller.
 11. A propulsion system mountedin a hull of a marine vessel, wherein the marine vessel defines awaterline in relation to the surrounding water, comprising: a) at leasttwo water intake openings defined in the hull below the waterline of thevessel; b) a collection chamber mounted within the hull; c) at least twowater intake conduits extending from said water intake openings to saidcollection chamber; d) at least two water discharge openings defined inthe stem of the hull; e) at least two water discharge conduits extendingfrom said collection chamber to said water discharge openings; f) atleast one impeller mounted in each of said discharge conduits; and, g) adischarge nozzle mounted to each said discharge opening.
 12. Thepropulsion system of claim 11 further comprising a plurality ofturbulator tabs mounted to each of said discharge nozzles.
 13. Apropulsion system mounted in a hull of a marine vessel, wherein themarine vessel defines a waterline in relation to the surrounding water,comprising: a) at least two water intake openings defined in the hullbelow the waterline of the vessel; b) a collection chamber mountedwithin the hull; c) at least two water intake conduits extending fromsaid water intake openings to said collection chamber; d) at least twowater discharge openings defined in the stern of the hull; e) at leasttwo water discharge conduits extending from said collection chamber tosaid water discharge openings; f) at least one impeller mounted in eachof said discharge conduits; and, g) side thrusters defined in the hulladjacent a stern of the hull on port and starboard sides of the hull,wherein said side thrusters are coupled to said discharge conduits. 14.A system for allowing access to an impeller portion of a propulsionsystem mounted within a marine vessel wherein the vessel defines awaterline surrounding the vessel, comprising: a) a conduit systemmounted within a hull of the marine vessel below the level of thevessel's waterline and containing the impeller portion of the propulsionsystem; b) a conduit extension section diverging from said conduitsystem with a first end in open communication with said conduit systemadjacent said impeller portion and an opposing end extending above thelevel of the vessel's waterline; and, c) a sealable hatch operablymounted to close said opposing end of said conduit extension.
 15. Theaccess system of claim 14 further comprising a plurality of valvesoperable to prevent water flow into or out of said conduit system. 16.The access system of claim 15 further comprising a pump connected tosaid conduit system and operable to evacuate water from said conduitsystem.
 17. The access system of claim 16 further comprising atransparent viewing panel mounted to said conduit system.
 18. A methodof propelling a hull of a marine vessel, comprising the steps of: a)drawing water into a propulsion system through at least three intakeopenings defined in the hull below the waterline of the vessel; b)transporting the water to a collection chamber mounted within the hull;c) feeding water from said collection chamber into at least two impellerportions; and, d) discharging the water through openings defined in thestem of the hull.